Available Answers

1. 1.

   Water occurs bath in the free and in the combined state - in solid, liquid or gaseous [vapour] state. Name the following forms of water.

   	Name
   1. Water occurring in the combined form in a mineral salt.
   2. A naturally occurring gaseous state of water other than water vapour.
   3. A liquid free state of occurrence of water above the earth's surface.
   4. A food product containing a large percentage of water in the combined form.
   5. An occurrence of water in the free state in the solid form other than ice.
   6. Water occurring in the liquid form in the free state below the earth's surface.

    

2. 2.

   

   The above diagram represents the water cycle. Give reasons for the following :

   1. Nature maintains the water cycle.
   2. Rain water is considered a very pure form of water compared to river and lake water.
3. 3.

   With reference to the following three properties of compounds - give reasons why water is considered a compound and not an element.

   Properties of compounds	Water as a compound
   1. Always homogenous with particles of one kind.
   2. Have a definite set of properties and components do not retain their original properties.
   3. The components can be separated by chemical means only.

    

4. 4.

   Water found in the natural state is called 'natural water' - while that which has received some form of treatment is called 'treated water'.

   Name the following:

   	Name
   1. Two sources of natural water other than rain water, river and lake water.
   2. The purest form of treated water free from all minerals solutes prepared by condensing steam.
   3. A form of treated water prepared by filtration followed by chemical treatment and is generally used for drinking purposes.
   4. An acidic gas used for killing germs present in the water in swimming pools.

    

5. 5.

   The diagram below represents the - dissolution of sodium chloride in water.

   With reference to the diagram -

   Match Column I with the meaning of the terms in Column Il.

   Column I	Column II
   A: Solute 'Y'	1. The substance which dissolves in the solvent to form a solution.
   B: Solvent 'X'	2. A homogenous mixture of a solute in a solvent.
   C: Solution 'Z'	3. The liquid or medium of dissolution which allows the solute to dissolve in it to form a solution.

    

6. 6.

   Select the correct statement in the table given below - for the properties of a true solution.

   True solution
   1. A true solution is	a] clear and homogenous in nature
   	b] translucent and heterogenous in nature
   2. The particles in a true solution	a] are molecular, and can be seen under a microscope
   	b] are molecular, cannot be seen under a microscope
   	c] pass through the pores of a filter paper, and slowly settle down
   3. The solute present in the solvent of a true solution can be recovered by	a] chemical and not by physical means
   	b] physical and not by chemical means
   4. A true solution is a	a] compound
   	b] mixture